Back and neck pain may cause disability and discomfort which may affect an individual's lifestyle. There are various levels of back and neck pain, from a low-level annoyance to extreme discomfort and debilitating pain. Depending on the type of pain and the cause of the pain, multiple options may be available to reduce and/or treat back and neck pain. Where conservative non-invasive techniques are inadequate, surgical treatment options may be available to reduce or eliminate such back and/or neck pain. For example, surgical treatment options may be used to decompress a nerve root, stabilize a lumbar or cervical joint, reduce a deformity of the spine, etc.
The degeneration, rupture or herniation of the intervertebral discs of the spine may cause back or neck pain. One exemplary type of lower back pain is due to degeneration of lumbar discs in the spine. Surgical options, such as lumbar fusion, may be available to relieve such lower back pain.
Two common types of lumbar fusion are postlateral fusion (PLF) and interbody fusion, including anterior lumbar interbody fusion (ALIF) and posterior lumbar interbody fusion (PLIF). In the lumbar fusion methods, described briefly below, a metal construct is often used to temporally stabilize the motion segment while awaiting development of a rigid osseous construct.
PLF may include positioning a bone graft external to the ruptured disc such that adjacent spinal bones (spinal segments) grow together. Screws and plates, such as pedicle screws, may be used to stabilize and prevent motion of adjacent spinal bones as they fuse together. Because PLF is not an interbody fusion, the surgery may be easier. However, PLF may not relieve back pain in some situations because the damaged disc remains intact within the spine and may continue to cause discomfort.
Each of the interbody fusions includes inserting a bone graft or similar object directly into the disc space. ALIF is an interbody fusion where the incision is through the front side of the body, such as through the abdomen. Typically, a three to five inch incision may be made on the abdomen. Through this incision, one or more lumbar discs may be removed. The discs may be replaced with a bone graft and/or a fusion cage. Because the large blood vessels to the lower extremities lay on top of the spine, the skill of a vascular surgeon may be needed to gain access to the spine. Moreover, there may be an increase in the risk of complications, such as hemorrhage, due to the close proximity of the large blood vessels to the spine. The risk of other complications, including unintentional sympathectomy and retrograde ejaculation in males, may also increase.
PLIF is an interbody fusion where entry is through the backside of the body. Typically, a three to six inch long incision in the midline of the back may be cut to obtain access to the spine. Due to the backside entry, substantial retraction of the nerve roots is necessary to gain access to the disc space. PLIF may further require extensive bone removal to access the disc space, which may increase the possibility of posterior migration of a fusion cage. Furthermore, the backside entry often damages the muscle tissue surrounding the disc space and adjacent spinal bones. The damage to the surrounding muscles complicates and prolongs the recovery process. Additionally, there may be an increased risk in extensive blood loss due to the epidural veins over the disc space.
For both ALIF and PLIF, the quality of the adjacent spinal bones may affect the quality and success of the fusion. For example, conditions characterized with poor bone quality, such as osteopenia and osteoporosis, may significantly decrease fusion rates. As described above, the conventional fusion methods may result in complications, such as neurological, dural, osteal, and muscular complications. Moreover, in many situations, these procedures require long hospital stays.